Rotary compressor



1969 o. c. RINEHART ROTARY COMPRESSOR Filed Aug. 25. 1966 INVENTOR. DEAN C RI NEHART H15 ATTORNEY United States Patent 3,423,013 ROTARY COMPRESSOR Dean C. Rinehart, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Aug. 25, 1966, Ser. No. 574,966 US. Cl. 230-439 Int. Cl. F04c 23/02, 17/02 3 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to rotary compressors and is more particularly concerned with a hermetic rotary compressor particularly adapted for use in refrigerating systems and the like.

A well known type of rotary compressor comprises a cylindrical wall defining a compression cylinder, a rotor eccentrically mounted within the cylinder and a vane slidably mounted in the cylindrical wall for engagement of the inner end thereof with the periphery of the rotor to divide the cylinder into a high pressure side and a low pressure side. In the operation of such a compressor, it is necessary to maintain the vane in continuous sealing engagement with the rotor surface. For this purpose, there is normally employed one or more compression springs positioned between the outer end of the vane and a suitable fixed support means. Such spring means have been satisfactory for low displacement rotary compressors, in which the maximum distance between the rotor and the cylinder walls is relatively small and, during eccentric rotation of the rotor, the vane moves a relatively short distance in maintaining contact with the rotor. However, with higher displacement rotary compressors in which the maximum distance between the eccentric rotor and the cylinder wall is substantial, the vane must move through a longer stroke during each rotation of the rotor. In order to obtain the required biasing action under such conditions, the vane springs must be stiffer and larger and unless additional space can be provided for these springs, the safe stress limits of the springs may be exceeded with resultant spring breakage.

A primary object of the present invention is to provide a rotary compressor including improved v-ane biasing means requiring only a minimum safe spring force regardless of the compressor displacement.

Another object of the invention is to provide in a rotary compressor, vane biasing means which does not require the use of the usual compression springs.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularly in the claims annexed to and forming part of this specification.

In accordance with the illustrated embodiment of the invention, there is provided a rotary compressor including a cylindrical wall defining a compressor cylinder, a rotor eccentrically rotatable within the cylinder and a vane slidably mounted in the cylindrical wall between cylinder inlet and outlet ports for engagement with the rotor to divide the cylinder into high and low pressure sides. For

ice

maintaining the vane in continuous engagement with the rotor surface, there is provided a plunger which is slidably mounted in the cylindrical wall on the opposite side of the rotor from the vane and a spring yoke connecting the plunger and vane in such a manner that both the plunger and the vane are biased into engagement with the rotor in all positions of the rotor within the cylinder. Since the plunger and vane, contacting opposite sides of the rotor, oscillate or reciprocate together, the only change in stress on the interconnecting spring yoke results from the slight difference or variation in the length of the contact chords between the vane and plunger during rotation of the rotor. In accordance with a preferred embodiment of the invention, the plunger also functions as valve means for controlling the periodic injection of liquid refrigerant into the high pressure side of the cylinder.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which:

FIGURE 1 is an elevational view, partially in cross section, of a hermetic refrigerant compressor incorporating the present invention;

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1; and

FIGURE 3 is a schematic view of a refrigeration system including the compressor of the present invention.

With reference to FIGURES l and 2 of the drawing, there is shown a hermetic compressor casing 1 in which there is disposed a rotary compressor unit 2 connected by means of a drive shaft 3 to an electric motor 4.

The compressor includes a cylindrical wall 6 having an inner cylindrical surface 7 which, in combination with the upper and lower end plates 8 and 9, defines the annular compressor chamber 10. A rotor 11 driven by an eccentric 12 on the shaft 3 is contained within the cylinder .10. A vane 14 slidably disposed within a radial slot 15 extending through the cylinder wall 6 is adapted to engage the periphery of the rotor 11 and divide the cylinder 10 into a high pressure side 16 and a low pressure side 17.

Such a hermetic compressor is particularly adapted to be connected into a refrigeration system such as that shown in FIGURE 3 of the drawing so as to withdraw low pressure or gaseous refrigerant from an evaporator 18 through a suction line 19 and discharge high pressure refrigerant through a discharge line 20 to a condenser 21 in which the high pressure refrigerant is condensed to a liquid before passing through a capillary tube or other flow restricting means 22 to the evaporator 18. More specifically, the suction line 19 conducts low pressure refrigerant to the low pressure side 17 of the cylinder through a suction port 24 in the cylinder wall 6 on the low pressure side of the vane 14 while high pressure refrigerant from the high pressure side 16 of the cylinder is discharged through a discharge port 25 controlled by a discharge valve generally indicated by the numeral 26 into the interior of the casing 1. After flowing through and in heat exchange relationship with the motor 2, this high pressure refrigerant is conducted from the casing 1 by means of the discharge line 20 to the condenser 21.

In order to prevent leakage of high pressure refrigerant from the high pressure side 16 into the low pressure side 17 during rotation of the rotor 11 within the cylinder 10, it is necessary that the forward edge 29 of the vane 14 be maintained in continuous sealing engagement with the periphery of the rotor 11 regardless of the position of the rotating rotor within the cylinder 10. This requires that during each rotation of the rotor 11, the vane reciprocates between a forward position in which the vane extends into the cylinder 10 as illustrated in FIGURE 2 of the drawing and a retracted position in which the forward edge 3 29 of the vane is substantially flush with the cylindrical surface 7.

As has been previously indicated, the requirements of the spring means employed for biasing the vane into engagement with the rotor surface depends upon a number of factors including the length of the reciprocating stroke of the vane which in turn depends upon the displacement of the compressor, that is, the difference in the diameters of the rotor and cylinder.

In accordance with the present invention, there is provided an improved means for biasing the vane 14 into engagement with the rotor 11 including a spring arranged to apply a relatively constant biasing force to the vane without being subject to substantial stressing. More specifically, this means for maintaining the vane 14 in engagement with the rotor comprises a cylindrical plunger 30 slidably mounted in a cylindrical passage or opening 31 extending through the cylinder wall 6 on the opposite side of the rot-or from the vane 14 and having an inner end 32 adapted to engage and ride on the rotor 11 and a generally U-shaped spring yoke 33 having one end 34 removably bearing on the outer end 35 of the plunger 30 and the other end 36 similarly engaged with the outer end 37 of the vane 14. In the illustrated embodiment this yoke is made of spring Wire and an intermediate portion of the yoke rides in, and is supported by, a portion of a groove 39 in the outer surface of the cylindrical wall 6.

By this arrangement, the inner ends of both the vane 14 and the plunger 30 are maintained in continuous engagement with the periphery of the rotor 11 by means of the spring yoke 33. The yoke is designed to apply only sufiicient spring force to maintain the vane 14 in sealing contact with the rotor. Since the plunger and vane are on opposite sides of the rotor 11, eccentric rotation of the rotor within the cylinder causes the plunger 30 and the vane 14 to move in the same direction at the same time, that is, either to the right or to the left as viewed in FIGURE 2 of the drawing. The spring yoke 33 interconnecting these two members oscillates with them so that the stresses applied to the spring 33 are only those resulting from the slight change in the contact chord of the plunger and vane with this rotor during eccentric rotation of the rotor. The length of this chord is maximum when the rotor is in the position illustrated in FIGURE 2 of the drawing and the minimum when it is in a position 90 removed from the illustrated position. However, this difference is small and hence results in only a small flexing or stressing of the spring yoke 33. The plunger, of course, has a diameter much smaller than the height of the rotor so as not to interfere with the pumping operation of the rotor.

An additional advantage of this vane biasing means is that the entire biasing force of the spring 33 is applied only against opposite sides of the rotor 11 and is not transmitted to the shaft supporting bearing or bearings as is the case with the usual springs positioned for example within the slot between the rear end 37 of the vane and a suitable bearing surface adjacent the rear end of the slot 15.

In accordance with a preferred aspect of the present invention, the plunger 30 also functions as valve means for controlling the momentary or periodic introduction of condensed refrigerant into the high pressure side 16 of the cylinder 10.

As is described more fully in my prior Patent 3,109,297 issued Nov. 5, 1963 and assigned to the same assignee as the present invention, the injection of condensed refrigerant from the refrigerant condensing component of the refrigerant system directly into the high pressure side of the cylinder at a specific point in the compression cycle provides means for lowering the temperature of the high pressure refrigerant discharged into the casing from the compressor thereby providing improved cooling of the motor contained within the casing,

The plunger controlled means for injecting the liquid refrigerant includes a refrigerant passage formed in the cylinder wall 6 and having a first portion 40 extending upwardly through the plate 9 and the wall 6 into the cylinder opening 31 and a second portion 41, shown in dotted lines in FIGURE 2 of the drawing, having its out let or port 42 communicating with the high pressure side 16. The first portion 40 is connected by a line 45 including a flow limiting capillary 46 to the condenser means 21 ahead of the normal flow control means 22. An annular groove 43 in the plunger 30 is adapted to register with and interconnect the two passage portions 40 and 41 at the point when the plunger 30 is moved out of the cylinder 10 to its retracted position thereby functioning as valve means to permit the injection of liquid refrigerant from the con-denser 22 into the cylinder. The liquid refrigerant is injected into the high pressure side 16 of the cylinder only when the plunger is in its retracted position as illustrated in FIGURE 2 of the drawing and, following the teachings of my aforementioned patent, the port 42 is so positioned in the cylinder wall 7 that the liquid refrigerant is injected at a time when the pressure within the high pressure side 16 is above suction pressure and sufficiently below discharge pressure to permit the injection.

While there has been shown and described a specific embodiment of the present invention it will be understood that it is not limited thereto and is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention. What I claim as new and desire to secure by Letters Patent of the United States is:

1. A hermetically sealed refrigerant compressor adapted for use in a refrigeration system including refrigerant condensing means for condensing high pressure gaseous refrigerant from said compressor,

said compressor comprising a hermetic casing adapted to contain a high pressure refrigerant gas, a rotary compressor unit in said casing discharging high pressure refrigerant into said casing and a drive motor in said casing cooled by said high pressure refrigerant, said compressor unit comprising means including a cylinder wall defining an annular compression cylinder, a rotor eccentrically rotatable within said cylinder, spaced inlet and discharge ports communicating with said cylinder and a vane slidably mounted in said cylinder wall between said ports for engagement with said rotor to divide said cylinder into high and low pressure sides, means for maintaining said vane in engagement with said rotor comprising a plunger slidably mounted in said wall on the opposite side of said rotor from said vane for engagement with said rotor and movement by said rotor into and out of said cylinder and a spring yoke connecting said plunger and yoke and biasing both said plunger and said vane into engagement with said rotor in all positions of said rotor,

means for injecting condensed liquid refrigerant from said condensing means into the high pressure side of said cylinder during compression of refrigerant gas therein including an injection passage communicating with said high pressure side of said annular chamber and valve means associated with said plunger for effecting injection of a small quantity of liquid refrigerant into said cylinder when said plunger moves out of said cylinder.

2. The compressor of claim 1 in which said valve means comprises a recess in a Wall of said plunger registering with said passage when said plunger moves out of said cylinder.

3. In a rotary compressor comprising a cylindrical wall defining a cylinder, a rotor eccentrically rotatable within 5 6 said cylinder, and at least one vane slidably mounted in References Cited said wall for engagement with the periphery of said rotor; UNITED STATES PATENTS means to maintain sald vane in engagement Wlth said rotor comprising: 607,678 7/1898 Bralnerd 91-101 means slidably mounted in said wall on the opposite 5 644,016 2/1900 June et a1 91 101 side of said rotor from said vane, and 705,457 7/ 1902 Skowen 91 101 a generally U-shaped spring yoke connecting said last- 918,906 4/1909 Poppenhusen et 230 149 mentioned means and said vane and biasing both said 2,883,101 4/1959 Kosfelfi 230 149 last-mentioned means and said vane into engage- 3,105,633 10/1963 Denano 230139 ment with said rotor in all positions of said rotor, the outer surface of said cylindrical wall having a 10 DONLEY STOCKING Pnm'ary Examiner groove to at least partially receive and sli-dably sup- WILBUR J. GOODLIN, Assistant Examiner.

port a portion ofsaid yoke intermediate the portions thereof engaging said last-mentioned means and US. Cl. X.R.

said vane. 15 230145, 149 

